An attorney receives payment of $2,100 in advance of May 1st for services to be performed. During the month of May, one-third of the services are completed. The May 31st adjusting entry would include: A. a credit to service revenue of 1,400 B. a credit to service revenue of 700 C. a debit to unearned service revenue of 1,400 D. a debit to cash of 2,100 E. none of the above